Sliding door operator



March 8, 1960 R. E. SLOPA ETAL 2,927,733

SLIDING DOOR OPERATOR Filed May 26, 1958 5 Sheets-Sheet 1 March 8, 1960 R. E. sLoPA ET AL 2,927,738

SLIDING DOOR OPERATOR Filed May 26, 1958 5 Sheets-Sheet 2 a N t.

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' United SLIDING DOOR OPERATOR Robert E. Slopa and George W. Slope, Harvard, Ill.

Application May 26, 1958, Serial No. 737,891

11 Claims. (Cl. 268-53) "such a manner as to not apply a lateral thrust on the carriage which would tend to derail the same.

A more particular object of this invention is to provide a horizontal sliding door operator including a track and a carriage mounted on the track and which has an improved apparatus carried by the door and operative to engage the track when the door reaches its closed position, to move the door laterally of the track and into sealing engagement with the door frame.

Another object of this invention is to provide an im' proved carriage construction for suspending a horizontal sliding door therebelow and which permits limited movement of the door relative thereto in a direction laterally of the track and which is also arranged to enable rapid and accurate adjustment of the height of the door.

Still another object of this invention is to provide an improved apparatus operatively connecting an endless chain type drive to the door for moving the same between its open and closed positions and which enables disconnection of the drive from the door from a location at the inner side of the door to permit emergency manual operation.

These, together with various ancillary objects and advantages of this invention will be more readily appreciated as the same becomes better understood by reference to the following detailed description when taken in connection with the accompanying drawings wherein:

Figure l is a perspective view of the door shown installed and with parts broken away and shown in section to illustrate details of construction;

Fig. 6 is an enlarged perspective view of the cam mechanism for operating the door in a direction laterally of the track;

Fig. 7 is an enlarged fragmentary perspective view of the apparatus for operatively connecting the door to the endless chain type drive;

Fig. 8 is a fragmentary vertical sectional view through the door, taken on the plane 88 of Fig. 1;

Fig. 9 is a schematic diagram of an electrical circuit for controlling the door operator;

Fig. 10 is a fragmentary enlarged top plan View of a modified form of door operating mechanism;

Fig. 11 is a fragmentary front elevational view of the door operating mechanism of Fig. 10, with parts broken away and shown in section to illustrate details of construction;

Fig. 12 is a fragmentary end elevational view of the door operating mechanism and illustrating a modified form of drive apparatus;

Fig. 13 is a fragmentary sectional view taken on the plane 1313 of Fig. 12, and

Fig. 14 is a schematic diagram of an electrical circuit for controlling the drive apparatus of Fig. 12.

Reference is now made more specifically to the accompany drawings wherein there is illustrated a sliding door 15 which is supported and operated by a mechanism to be described hereinafter between a closed position overlying the door opening 16 and an open position uncovering the door opening. As is conventional, a frame including upright side member 17 and a horizontally extending top member 18 are attached to the wall 24 around the door opening. The frame members 17 and 18 are preferably formed with flat front faces and define a substantially flat sealing face around the sides and top of the door opening. The door is mounted for movement along a path generally parallel to the front face of the frame into and out of position overlying the door opening and provision is made for moving the door laterally into sealing engagement with the frame, as the door reaches its closed position. The door 15 also moves downwardly to seal against the floor 19 along the lower edge of the door, to thereby provide a tight closure suitable for use in refrigerated coolers and freezers.

In order to facilitate installation of the door and door operator, the door support track and the door operator are preferably arranged to be mounted on a common support rail, herein shown in the form of an elongated channel 22. The track and operator may conveniently be factory assembled onto the rail 22 so that it is only necessary to attach the rail in proper position above the door frame 18. As best shown in Fig. 4, the rail is attached to the wall 24, asby bolts 23 to extend above the top frame member 18 and in parallel spaced relation to the floor 19. A plurality of track support brackets 25 are secured to the rail 22 at longitudinally spaced points therealong, and an elongated track 28 is secured to the outer ends of the brackets 25.

The door 15 is supported on the track by means of carriages 33. These carriages include a generally rectangular frame 34 having a sleeve 35 extending downwardly therefrom and located at a point intermediate the ends of the frame and along one side thereof. Grooved rollers 36 are disposed within the frame 34 and rotatably supported on the frame by means of pins 37. As best shown in Figs. 4 and 5, the rollers engage the upper edge of the track 28 and the sleeve 35 extends downwardly along the front side of the track to a position adjacent the lower edge thereof.

In accordance with the present invention, the door 15 is supported on the carriage 33 in such a manner as to permit limited lateral movement of the door relative to the track. More particularly, generally L-shaped mountbetween the ears and pivotally mounted thereon by means of a pin 43. The pin 43 is preferably disposed substantially medially between the front and rear faces of the door and in an approximate vertical alignment with the track 28. A bolt 44 having a head on the upper end thereof extends downwardly through the sleeve 35 on the carriage and is threadedly attached to the pivot block 42 at one side of the pin 43 to vertically adjustably support the same on the carriage. As is apparent, the bolt 44 can be turned in opposite directions to raise and lower the door and thereby adjust the vertical height thereof. A collar 45 is disposed around the bolt 44 and is arranged to underlie the track 48 to prevent derailing of the carriage. A nut 46 is threaded on the bolt 44 and engages the collar 45 to secure the same to the underside of the sleeve 35. A set screw 47 is threaded into the pivot block 42, at the side of the pin43- opposite the bolt 44 and is, arranged to engage the mounting bracket 39 to limit relative pivotal movement between the block and the mounting bracket in one direction while permitting free pivotal movement in the other direction. A look nut 48 is provided for locking the set screw in its preseleeted adjusted position. As is apparent, each of the carriages 33 can tilt on their rollers 36 relative to the track 28. As the lower end of the sleeve 35 swings inwardly, the door 15 will be moved toward the frame members 17 and 18, the door pivoting above the pin 43 to remain in a substantially upright position as it is moved laterally of the track. A resilient sealing gasket, herein shown in the form of a hollow extrusion 49, is secured to the rear face of the door 15 along the top and sides thereof and arranged to engage the top and side members 18 and 17 of the door frame to seal thereagainst.

Provision is made for automatically moving the door 15 laterally of the track 29, as the door is moved to its closed position to form a tight seal between the door and the frame. In accordance with the present invention, the mechanism for moving the door laterally of the track is mounted on the door and arranged to engage the track at the rear side thereof. With this arrangement no ap preciable lateral pressure is applied to the carriage 33 so that movement of the door laterally of the track does not tend to derail the carriage.

More particularly, a pair of generally L-shaped brackets 51 are attached to the upper edge of the door 15. adjacent opposite ends thereof, and carry an upstanding post 52 thereon (see Fig. 6). A cam lever 53 is mounted on each of the posts for horizontal swinging movement relative thereto, as by a stud 54. A cam finger, herein shown in the form of a roller 55, is mounted on therear end of each of the levers 53 and extends upwardly therefrom. The roller is rotatably'supported on a stub shaft 56 which is threaded into the cam lever 53 and locked thereto by a nut 57. A cam plate 58 is rigidly attached to the track 28, adiacent opposite sides of the door opening and extends downwardly from the track into the path of movement of the rollers 55, when the door is in a position overlying the door opening 16. As best shown in Fig. 4, the cam plates 58 areconveniently bolted to the track 28 and spacer washers 59 are interposed between the track and the cam plate to adjust the position thereof relative to the track.

The cam levers 53 adjacent opposite ends of the'door are operated in unison by means of a link 61 which is pivotally attached to the ends of thecam levers remote from the rollers 55. For this purpose, a clevis 62 is preferably threadedly connected to one end of the link 61, which clevis is pivotally attached to one of the cam levers A generally rectangular member 64 isthreadedlyattached to the other end ofthelink 61and'p'ivotally connected by a'pin 65 to thecamlever 53 atthe other'end of the door. A'guide bracket 66- is attached to the door, intermediate the ends thereof and hasa slot 67 (see Fig. therein which is elongated in a direction 4 perpendicular to the door 15 to slidably receive the link 61 and to permit limited lateral movement of the link as the cam levers swing about the posts 52.

A drive mechanism is provided for moving the door between its open and closed positions and includes a generally I-shaped frame 71 which is carried by brackets 72. As best shown in Fig. 4, the brackets 72 are welded or otherwise secured to the upper edge of the rail 22, to properly position the brackets and drive with respect to the rail, and supplemental fasteners 73 are provided for securing the brackets to the supporting wall 24. A drive motor 75 is mounted on one end of the frame 71 and opposed pairs of bearings 76 and 77 are mounted on the other end of the frame. A shaft 78 is rotatably supported in bearings 76 and a pulley79 is mounted on the shaft and operatively connected thereto through a friction clutch (not shown). The motor drive pulley 81 is connected to the pulley 79 through a belt 82. A shaft 83 is jou-rnaled in bearings 77, which shaft is drivingly connected through 'a chain and "sprocket arrangement $4 to the shaft 78 to be driven thereby. A door drive sprocket 87 is attached to the other end of the shaft and drives a chain 88 operatively connected to the door, in a manner to be described more fully hereinafter. The other end of the chain, as best shown in Fig. 2, is entrained over an idler sprocket 89 which is adjustably mounted by a fixture 91 on a mounting bracket 92. This last-mentioned bracket is also conveniently welded or otherwise secured to the rail 22.

A rotary limit switch 95 is mounted on the I-shaped bracket 71 and is operatively connected through a chain and sprocket arrangement 96 to the main shaft 83 which drives the sprocket 87. With this arrangement, it will be seen that the motor 75, when energized, will rotate the sprocket 87 in a direction corresponding tothe direction of rotation of the motor to effect opening or closing of the door. The rotary limit switch 95 will be operated in accordance with the position of the door drive chain 88 and is electrically connected to the motor operating circuit in the conventional manner to deenergize the motor when the door reaches its open or closed positions. If the door strikes an obstruction prior to reaching its open or closed positions, the clutch connecting the pulley 79 to the shaft 78 will slip and prevent damage to the parts.

The apparatus thus far described for mounting the door and for operating the latter between its open and closed position is the same for both embodiments illustrated and like numerals are used to designate corresponding parts. In the embodiment illustrated in Figs. 1-9., one run of the operating-chain 88'is dii'ectlyc'onnected to the door 88. As best shown in Fig. 7, a guide sleeve 101 is attached by abraeket 102 to the'front face of the door 15 and guidabl'y'receives the lower run of the chain 88. The chain is formed with'anenlarged connector link 103 which is tapered at opposite ends thereof to facilitate guiding into the sleeve 101 and a locking pin 104 is slidably mounted in the sleeve and arranged to extend into a bore in the connector link 103 to lock the same to the sleeve and thereby drivingly connect the door to the chain. The pin 104 is yieldably urged into its locked position by means of a spring 105 which is interpoesd between a collar on the pin and a guide ring 107 carried by the bracket 102. It is a feature of the present invention that the driving connection between the chain 88am! the door 15 can be selectively disconnected from a point inside of the door to enable emergency manual operation of the door in the event someone is inadvertently locked in the cooler or freezer or if, for any other reason, it is desired to manually operate the door as by reason of a power ur Ahexiblecable'lw is'attachedto'a ring'111 at the lower end of the locking pin 104 andthe cable extends downwardly along the frontside of the'doorand over a horizontally disposed guide pin or roller 113' (see Fig. 8) and through a guide tube 114 to a point at the inside of the door 15.

A recess 116 is formed at the inner face of the door and a handle 117 is mounted in the recess and operatively connected to the inner end of the cable 109 to permit drawing of the cable and retraction of the locking pin 104 from a point inside of the door.

An apparatus is provided for automatically operating the cam levers 53 to move the door laterally of the track, as the door approaches its closed position, to thereby move the door into snug sealing engagement with the door frame. For this purpose, a stop bar 120 is attached to the end of the track and extends laterally and downwardly thereof into the path of movement of the link 61. An adjustable finger 122 is threadedly attached to the rectangular member 64 and arranged to engage the stop, as the door approaches its closed position. This causes the cam levers to pivot in a clockwise direction as viewed in Figs. 2 and 3 and moves the rollers 55 on the inner ends thereof into engagement with the respective cam plates 58 and forces the door in a direction toward the door frame. The carriage 33 tilts slightly relative to the track and the door pivots about the pin 43 relative to the carriage to permit the aforementioned lateral movement of the door while maintaining the sealing gaskets on the door in parallel relation to the frame members 17 and 18. When the motor 75 is operated in the reverse direction, the door is retracted to its open position. A spring 124 is interposed between the guide bracket 66 and a collar 125 on the link 61 to urge the cam levers 53 to their release position. A stop collar 126 is provided on the link and engages the guide 66 to limit movement of the link relative to the guide and normally maintains the cam levers 53 in the position shown in Fig. 3.

The aforedescribed operator elfects movement of the upper edge of the door between an opened and closed position and also in a direction laterally of the track into engagement with the door frame. The lower edge of the door is urged against the frame by means of wedges 129 which are attached to the door adjacent the lower edge thereof and which engage resiliently supported wedge blocks 131 mounted on the floor adjacent opposite sides of the door opening, as the door reaches its closed position. A seal is effected between the bottom of the door and the floor 19 by inclining the track 28 slightly so that the door moves downwardly as it approaches its closed position to effect a seal between the gaskets at the lower edge of the door and the finished floor 19.

One suitable control circuit for the motor 75 is shown diagrammatically in Fig. 9. As previously described, the motor 75 is arranged for reversible operation and one of the motor conductors 156 is connected directly to the source of power. The other motor conductors 157 and 158 are connected through limit switches 95a and 95b and conductors 159 and 160 to a three-way reversing switch 161, which reversing switch is connected through conductor 162 to the source of power. The reversing switch is operated from a position establishing a circuit to one of the conductors 159, 160 to a position establishing a circuit to the other of said conductors, each time the solenoid 163 is energized. The solenoid 163 is energized through a low voltage circuit power for which is supplied from a transformer 164 having its primary 164a connected to conductors 156 and 162. The secondary 164b is connected to the solenoid 163 and a plurality of normally-open parallel-connected switches 166, 167, and 168 are provided for controlling energization of the solenoid. Switches 166 and 167 are located at relatively opposite sides of the door to enable actuation of the door operator from either inside or outside the cooler or freezer, and may be operated manually or by a photo-electric cell or similar device. The switch 168 is arranged to be operated by the safety edge 169 on the leading edge of the door 15. For this purpose, the switch 168 is operated by a'solenoid 172 which is energized from the secondary of transformer 173 under the control of the normally open circuit breaker in the safety edge. The primary of transv 6 former 173 is connected to conductors 156 and 157. When the reversing switch 161 and the limit switches 95a and 95b are in the positions shown in Fig. 9, the door is in its closed position. When one of the switches 166, 167 is closed, the reversing switch 161 is moved to establish a circuit to the other conductor 160 and energizes the motor in the reverse direction through limit switch b until the door reaches its open position at which time switch 95b opens and stops the door. As the door moves away from its closed position, limit switch 95a closes. When one of the switches 166, 167 is again operated, the reversing switch moves back to its first-mentioned position and establishes a circuit to the motor through limit switch 95a to energize the same in the forward direction to close the door. When the door reaches its closed position, limit switch 95:: opens and stops the motor. However, if the safety edge 169 engages an obstacle, the switch 168 will be closed thereby operating the reversing switch 161 and efl ecting reversal of the direction of movement of the door.

In the aforedescribed arrangement illustrated in the embodiment of Figs. 1-9, the extension of the door continues after the finger 122 engages the stop so that, during final movement of the door to its closed position, the door is moved laterally of the track while it is being extended. With the arrangement disclosed in Figs. 10 and 11, the door is extended to a position overlying the door opening and the door thereafter moved laterally of the track into engagement with the door frame to minimize wear and tear on the gaskets. This is conveniently effected by mounting a chain guide sleeve 141 on the link 61 by means of a bracket 142. The chain 88 extends through the guide sleeve and the link 103 thereof is arranged to be locked to the guide sleeve by a pin 143 which is slidably mounted in the sleeve 141 and yieldably urged to its locked position by means of a spring 144. The aforementioned operating cable 109 may be connected to the pin 143 to selectively release the same. As is apparent, the chain 88, in the embodiment of Figs. 10 and 11, is drivingly connected to the link 61 to extend and retract the latter and a spring 148 is interposed between the guide bracket 66 and a collar 149 on the link so as to yieldably urge the door toward its closed position, as the link 61 is extended, that is moved to the right as viewed in Figs. 10 and 11. A stop collar 152 is provided on the link 61 and engages the guide bracket 66 to move the door 15 to its open position, as the link 61 is retracted.

A stop is attached to the door frame and arranged to engage the leading edge of the door 15, when the latter reaches its extended position. Further movement of the chain 88 will extend the link 61 relative to the door, and against the compression of the spring 148. As the link is extended relative to the door, the cam levers 53 are moved in a counterclockwise direction as viewed in Fig. 9 into engagement with the cam plates 58 to thereby move the door laterally of the track and into snug sealing engagement with the door frame. When the chain 88 is thereafter retracted to open the door, the spring 148 is operative to initially move the link relative to the door and thereby move the cam levers 53 to their release position. The stop 152 on the link then engages the guide bracket 66 and retracts the door to its open position. The sealing of the lower edge of the door may conveniently be efiected in the manner previously described in connection with the embodiment of Figs. 1-9.

A modified drive apparatus is illustrated in Figs. 12-14 and is adapted for use with either the door operator of Figs. 1-9 or the door operator of Figs. 10 and 11. The drive apparatus comprises a drive motor 201 which is mounted at the underside of a plate 202 carried by the mounting brackets 72. The drive motor is of the gear head type in which the gear head 203 has a laterally extending output shaft 204.

spawns The door drive sprocket 206 and limit switch drive sprocket 207 are clutch connected to the shaft 204. In particular, the sprockets 206 and 207 are non-rotatably connected to each other, as by welding, and are rotatably supported on the shaft 204 in abutting engagement with a shoulder 209 thereon. A clutch plate 211 is disposed on the shaft and is adjustably pressed into frictional engagement with the sprocket 206 by a dome spring 212 and an adjusting nut 213. The sprocket 206 is drivingly connected by the chain 88 to the door 15, in the manner previously described.

A bracket 215 is attached to theplate 202 and extends downwardly therefrom to support the rotary limit switch 217. A chain 218 connects the sprocket 207 to the limit switch sprocket 219 to operate the limit switch in accordance with the position of the door. One end of the chain guard 221 is attached to the brackets 72, as by an angle iron 223, and has an opening 224 therein to accommodate the limit switch shaft.

The motor 201 illustrated herein is of the three-phase type and is reversibly energized by the control circuit shown in Fig. 14. The power conductors 231-234 are connected through a solenoid operated reversing switch 235 and conductors 236238 to the motor 201. As shown, the reversing switch includes first and second sets of contacts S and S which are normally open and arranged to be closed by plungers 241 and 242 operated by solenoids 243 and 244. The solenoids 243 and 244 are respectively connected through limit switches 217a and 2171) to a three-way switch 245. The limit switches 217a and 217b are normally closed and respectively operated to their open position by the aforedescribed chain 218 and sprocket 219 when the door reaches its closed and its open positions. As shown, the switch 217a is opened as occurs when the door reaches its closed position. The three-way switch 245 is operated by a solenoid 248 under the control of switches 251, 252 and 253. The last-mentioned switches are normally open and are connected in parallel with each other and through a low voltage circuit including the solenoid 248 to the secondary of transformer 256. Switches 251 and 252 are positioned at the inner and outer sides of the door to permit operation of the latter from either side thereof and may be manually operated or automatically as by a photoelectric cell. The switch 253 is operated by a solenoid 255 which is connected through another low voltage circuit including the safety edge 169 to the secondary of transformer 256.

The aforedescribed circuit controls the operation of the motor to energize the same in one direction and effect movement of the door toward its closed position when one of the switches 251 or 252 is closed. Upon reaching its closed position, limit switch 217a opens and stops the motor. When the switch 251 or 252 is again closed, the three-way switch 245 is operated and operates the reversing switch 235 to energize the motor in the opposite direction to open the same. When the door reaches its open position, switch 217b is opened and stops the door.

The doors 15 are frequently very heavy and in order to rapidly stop the same, when the safety edge is actuated, there is provided a solenoid operated brake 261 on the motor 201. The brake is of conventional construction and is normally applied to stop rotation of the-motor and provision is made for energizing the brake solenoid to permit rotation of the motor when the latter is energized. This may be conveniently effected by connecting the brake solenoid to conductors 236 and 237 so that the solenoid is energized when the motor is energized in either direction of operation of the latter. Whenthe motor is de-energized, as occurs when the.safety'edge-169..opcrates switch 255, or When'either' limit. switch 217a -or 2171) is opened, the brake SUl6BOid- .lS 'd6.-EnBIgiZ- d and stops the motor. 'Since the motor is of the gear head type (preferably employing a worm gear drive to inhibit driving the motor by turning its output shaft) and is con- 8-: nected through sprocket 2.06 to the door operating chain 88, it will be seen that the door will be rapidly stopped when the motor is tie-energized. In this manner, the likelihood of injury topersons or property in the path of the door is minimized.

From the foregoing it is apparent that there has been provided an apparatus for automatically moving the door between its open and closed positions and for also mov ing the door laterally of the track into snug sealing en gagement with the door frame. In addition, since the mechanism for moving the door laterally of the track operates directly between the door and the track, it is apparent that the lateral force required to move the door into engagement with the frame will not tend to derail the door support carriage.

We claim:

1. A sliding door operating mechanism comprising a track, means for mounting said track above a door open-t ing, a carriage mounted on said track for movement therealong, means mounting the door on the carriage for movement therewith and for limited movement laterally of the track, means defining a rearwardly facing cam face rigid with said track, a cam finger adapted for engagement with said cam face, means mounting said cam finger on said door for limited movement relative thereto in a direction crosswise of said door, means rigidly connected to said door for moving said door along said track, and means responsive to movement of said door toward its closed position and operative when said door reaches a preselected position in advance of its closed position for thereafter moving said cam finger crosswise of said door and into engagement with said rearwardly facing cam face to move the door laterally of the track and into tight sealing engagement with the door frame simultaneous with the movement of the door along thetrack to gradual- 1y retard movement of the door to its fully closed position by the braking action of the door rubbing against the door frame.

2. In combination with a door, a track, means for mounting the track above a door opening, a carriage mounted on said track for movement therealong, means mounting said door on said carriage for movement therewith and for limited movement laterally of said track, a cam lever mounted on said door for pivotal movement about an upright axis, means defining a rearwardly facing cam plate rigid with said track, means on said cam lever engageable with said cam plate for moving said door laterally of-said track as said lever is moved about its pivot axis from a first position to asecond position, means rigidly connected tosaid'door'for moving said door along said track, and means responsive to movement of said door toward its closed position and operative whensaid door reaches a preselected position in advance of its closed position for thereafter moving said cam lever from said first position to said second position to thereby movesaid door laterally of said track and into sea-ling engagement with the frame around the door opening simultaneous with the movement of the door along the track to gradually retard movement of the door to its fully closed position by the braking action of the door rubbing against the door frame.

3. A sliding door operating mechanism comprising-a track, means for mounting the track above a door opening, a carriage mounted onsaid track, for movement'there! along, means for mounting adooron-the=carriage=formovement therewith and for limited movement laterally of said track, a cam lever mounted on said door adjacent each end thereof for pivotal movement about an upright axis, a link bar pivotally attached to one end of each of said levers, means defining a rearwardlyfacing camfacerigid withsaid track-adjacent each side of-"the door'open' ing, means on .thezother ends-of-said'cam-leverswngageable with a-respective one of saideamfaces'for moving said door laterally of said track in response to movement of said levers from a first position to a second position,

i means rigidly connected to said door for moving said door along said track, and means responsive to movement of said door toward its closed position and operative when said door reaches a preselected position in advance of its closed position for thereafter moving said cam levers from said first position to said second position to thereby movethe door laterally of said track and into engagement with the door frame simultaneous with the movement of the door along the track to gradually retard movement of the door to its fully closed position by the braking action of the door rubbing against the door frame.

4. A sliding door operating mechanism comprising a track, means for mounting the track above a door opening, a carriage mounted on said track, for movement therealong, means for mounting a door on the carriage for movement therewith and for limited movement laterally of said track, a cam lever mounted on said door adjacent each end thereof for pivotal movement about an upright axis, a link bar pivotally attached to one end of each of said levers, means defining a rearwardly facing cam face rigid with said track adjacent each side of the door opening, means on the other ends of said cam levers engageable with a respective one of said cam faces for moving said door laterally of said track in response to movement of said levers from a first position to a second position, "means rigidly connected to said door for extending the same to its closed position and for retracting the same to its open position, and stop means engageable with said link bar when the door reaches a position in advance of its closed position and operative as said door is extended to its fully closed position for moving said cam levers from said first position to said second position to thereby move the door laterally of said track and into engagement with the door frame simultaneous with the movement of the door along the track to gradually retard movement of the door to its fully closed position by the braking action of the door rubbing against the door frame.

5. The combination of claim 4 including spring means yieldably urging said link bar relative to the door in a direction opposite the direction of movement of the door to its closed position to move said cam levers from said second position to said first position to thereby permit said door to move away from the door frame as the door is retracted.

6. A sliding door operating mechanism comprising a track, means for mounting the track above a door opening, a carriage mounted on said track for movement therealong, means for mounting a door on the carriage for movement therewith and for limited movement laterally of said track, a cam lever mounted on said door adjacent each end thereof for pivotal movement about an upright axis, a link bar pivotally attached to one end of each of said levers, means defining a rearwardly facing cam face rigid with said track adjacent each side of the door opening, cam fingers on the other ends of said levers engageable with a respective one of said cam faces for moving said door laterally of said track in response to movement of said levers from a first position to a second position, means on said door defining a guide slidably receiving said link bar intermediate the ends thereof, means connected to said door for extending the same to its closed position and for retracting the same to its open position, stop means engageable with said link bar when the door reaches a position in advance of its closed position and operative as said door is extended to its fully closed position for moving said cam levers from said first position to said second position to thereby move the door laterally of said track and into engagement with the frame about the door opening simultaneous with the movement of the door along the track to gradually retard movement of the door to its fully closed position by the braking action of the door rubbing against the door frame, and spring means engaging said link bar and said guide yieldably urging said link bar relative to said door in a direction opposite the direction of movement of the door to its 10 closed position to move said levers from said second position to said first position.

7. A sliding door operating mechanism comprising a track, means for mounting the track above the door opening, a carriage comprising a frame disposed along the front side of said track, a grooved roller mounted on one side of said frame and engageable with the upper edge of said track, said frame having a vertically extending bore therein, a bolt rotatably received in said bore and having a head on the upper end thereof supported on said frame, a pivot block threadedly attached to the lower end of said bolt and extending laterally of said one side of said frame below said track, means pivotally mounting a door on said block for swinging movement relative thereto about an axis parallel to said track and laterally oifset from said frame, means for moving said door along said track, and means responsive to movement of said door to its closed position for moving the door laterally of said track into sealing engagement with the frame around the door opening.

8. The combination of claim 7 including a plate on said bolt adapted to extend laterally thereof and underlie said rail to prevent dislodgement of the carriage therefrom, and a nut on said bolt for locking said plate to said frame after said carriage is mounted on said rail.

9. In a sliding door operating mechanism, the combination of a door, a track, means for mounting the track to extend alongside a door opening, a carriage mounted on the track for movement therealon means for mounting the door on the carriage for limited movement laterally of the track, a plurality of cam levers mounted on the door for pivotal movement about an axis parallel to the plane of the door, means defining rearwardly facing stationary cam plates, means on one end of said levers engageable with said plates to move the door laterally of the track in response to movement of said levers from a first position to a second position, link means connecting other ends of said levers, spring means yieldably urging said link means relative to the door in a direction opposite the direction of movement of the door to its closed position to move the levers to said first position, a motor, a chain rigidly connected to the door and operatively connected to said motor for moving the door along the track, stop means engageable with said link means before the door reaches its fully closed position for moving said levers from said first to said second position thereof to thereby move the door laterally of the track and into sealing engagement with the frame around the door opening simultaneous with the movement of the door along the track to gradually retard movement of the door to its fully closed position by the braking action of the door rubbing against the door frame, brake means for stopping said motor, means for operating said brake means to stop the motor only when the motor is de-energized, and means including a limit switch for de-energizing said motor as said door approaches its fully closed position.

10. In a sliding door operating mechanism, the combination of a door, a track, means for mounting the track to extend alongside a door opening, a carriage mounted on the track for movement therealong, means for mounting the door on the carriage for limited movement laterally of the track, a plurality of cam levers mounted on the door for pivotal movement about an axis parallel to the plane of the door, means defining rearwardly facing stationary cam plates, means on one end of said levers engageable with said plates to move the door laterally of the track in response to movement of said levers from a first position to a second position, link means connecting the other ends of said levers, spring means yieldably urging said link means relative to the door in a direction opposite the direction of movement of the door to its closed position to move the levers to said first position, a motor, a chain rigidly connected to the door and operatively connected to said motor for moving the door along the track, stop means engageable with said link means before the door reaches its fully closed position for moving said levers from said first to said second position thereof to thereby move the door laterally of the track and into sealing engagement with the frame around the door openingvsimultaneous with the movement of the door along the track to gradually retard movement of the door to its fully closed position by the braking action of the door rubbing against the door frame, said link means including a finger adapted for engagement with said stop means and adjustable longitudinally of said link means to selectively vary the position of the door along the track at which the levers are operated to move the door laterally of said track.

11. In a sliding door operating mechanism, the combination of a door, a track, means for mounting the track to extend alongside a door opening, a carriage mounted on the track for movement therealong, means for mounting the door onthe carriage for limited movement lateral y of the track, a p u ality .Q a rs moun d o the door for pivotal movement about an ,axis'parallel to the plane of the door, means defining rearwardlyfacing stationary cam plates, means on one end of said levers engageable with said plates to move the door laterally of the track in response'to movement of said levers from a first position to a second position, link means connecting the other ends of said levers, spring means yieldably urging said linl; means relative to the door in a direction opposite the direction of movement of the door to its closed position to move position, a motor, a chain rigidly connected to the levers to said first the door and operatively connected to said motor for moving the door along the track, stop means engageable with said link means before the door reaches its fully closed posimovement of the door to its fully the braking action of the frame, a safety connected to th safety closed position by door rubbing against the door edge on said door, and circuit means edge for reversing said motor hen th aistyes s resse an o ec o h y pid reverse th direction of j ovement ofsaid door.

Betersm s fitted ;.'u. th gi nt t Pa n UNITED STATES PATENTS OConner Oct. 7, 1952' Johnson et a1. July 17, 1956 Torburn Oct. 9, 1956 Lawick u Apr. 23, 1957 Lesage July 15, 1958 

